Microsoft executives this week continued to let slip details about the progress of Longhorn, the successor to Windows.

On Wednesday, an e-mail sent to customers and partners detailed the intense work Redmond is doing to answer criticism that its Windows XP operating system is prone to attacks and hijacking. The company is now referring to XP Service Pack 2 a release rather than an update.

"The impact of reallocating some resources from Longhorn to Service Pack 2 means that the first beta for Longhorn is now expected in early 2005 instead of late 2004," a Microsoft spokesperson told internetnews.com.

On Tuesday, Microsoft chairman Bill Gates told an audience that speculation about Longhorn's delay until 2006 is "probably valid." The spokesperson also confirmed that an alpha build of Longhorn would appear this year.

He would not confirm the 2006 ship date for Longhorn, but did say that those "speculations" remain "valid." He added, "Microsoft plans to ship Longhorn when it meets the quality that customers require, and when internal development and test criteria are fully satisfied. It's an innovation-driven project, not a date-driven one."

The spokesperson said that it's too early in the development process to determine what features will be in the final product, but the major elements, WinFS, Avalon and Indigo, will be there. He said that news reports of features being cut from the next-generation operating system would be "very minor things."

"The big push right now is Service Pack 2," he said. "It's still on track and due later this year."

There still is no exact date for its release, but the spokesperson pointed out that the technical preview program for the release has begun, and there will be a Release Candidate 2 version before the final Service Pack is released.